Dual mode electrostatic printing

ABSTRACT

A dual operating mode electrostatic printer wherein input information from a remote apparatus is printed a line at a time at high speeds in a first operating mode and wherein information from a keyboard is printed a character at a time in a second low speed operating mode.

United'States Patent [151 3,686,678

[56] ReferencesCited Robbins et a1. 1451 Aug. 22, 1972 41 DUAL MODE ELECTROSTATIC 2,831,424 4/1958 MacDonald ..95/4.5 Ux

PRINTING 2,909,263 10/1959 Wheeler ..197/183.

[72] Inventors: Neal R. Robbins, Webster; Howard Daniel Ring, Rochester; Gerard C.

Wright, 'Penfie1d; Theodore M.

I Ceelen', Rochester, Stuart E.

Hotchkiss Williamson an f Primary Examiner-Samuel S. Matthews [73] Assignee: Xerox Corporation, Rochester, NY. Assistant Examiner-Monroe'l-l- Hay s Attorney-James J. Ralabate, Irving Keschner and [22] Filed. Marchrl0, 1969 1 I John EBeck [21] Appl. No.: 805,695

I 571 ABSTRACT [52] US. Cl. ..345/74 ES, 178/30 7 A dual operating mode electrostatic printer wherein ['51] Int. Cl. .;...,....-......'G01d 15/06 input information from a remote appara usjis printed a [58] Field of Search ..95/4Q5; 355/3, 7; 346/74 ES, line'at a time at high speedsin a first operating mode 346/74 E, 7.4 CH, 74 8,74 SB, 74 SC; and wherein information from a keyboard. is printed a 197/ 183;,178/30 character at a time in asecond low speed operating I mode.

. a 1 8Claims,6Drawingligures ,UNITED STATES PATENTS i 1. 1,355,365 1 1;92 0 Taylor Patented Aug. 22, 1972 3,686,678

3 Sheets-Sheet J.

PAPER OUT PAPER I N INVEN 70R: NEAL R. ROBBINS THEODORE M. CEELEN AGENT Patented Aug. 22, 1972 3 ShQtS-ShGBt 5.

. PAPER FEED F/G 3 F/GI 3A DUAL MODE ELECTROSTATIC PRINTING.

BACKGROUND OF THE INVENTION energized electrodes. In this manner, a charge pattern is formed on the dielectric material in accordance with the presence, absence, or. intensity of the potential applied across the electrodes. This charge pattern, or

electrostatic latent image, may then be developed into visual form by the application to the web or sheet of an electroscopic powder, which adheres in conformance with the charge pattern. The resultant developed image, may, if desired, be converted into a permanent record by, for example, the application of heat, if either the dielectric web or the powder is heat softenable, or by coating the charge bearing surface of the web with a fixative, or by softening the web and/or the powder with a solvent vapor. The printing electrodes may comprise a plurality of pins arranged to produce characters through a selective time energization of the pins, the pins being physically separated and electrically isolated from each other.

High operating speed, which is generally desirable in any type of printing apparatus, is critically important in apparatus which directly record the output of electronic computers, telemetering receivers, and the like, because of the high rate with which data for printing are produced by such apparatus. The prior art printing apparatus which utilize the electrostatic printing technique are usually limited in speed due to the displacements. of movable members or material masses static printing apparatus which enables high speed prin-- occurring in the printing operation. The mechanical inble to develop printing apparatus having a dual mode of operation, the high speed mode referred to hereinabove, and a compose mode therein activation of a keyboard will incrementally produce characters a character at a time on a recording medium.

SUMMARY OF THE INVENTION This invention provides a novel drive mechanism for use in printing apparatus and in particular to a dual mode stylus drive system wherein a high speed mode is utilized for receiving and printing transmitted information from remote apparatus and wherein the low speed mode, or compose mode, is utilized to incrementally produce characters a character at a time as the stylus traverses the width of a recording medium in response to a locally generated input.

It is an object of the present invention to provide a drive mechanism capable of effecting accurately timed reciprocation of a stylus across the surface of a recording medium.

It is a further object of the present invention to provide a high speed stylus drive mechanism for use in an electrostatic printer.

It is still a further object of the present invention to provide a dual mode stylus drive mechanism wherein the first mode input information may be printed at very high speeds and wherein in a second, or compose mode, characters are selectively printed a character at a time.

It is an additional object of the present invention to provide a novel stylus support member which provides means to dampen the speed of the stylus carriage'near the ends of the support member and further provides a method for reducing dirt contamination in the carriage tout of received information in one mode and operates to selectively compose, or type, information on a recording medium in a second mode.

It is still a further object of the present invention to provide means to compensate for the non-uniform speed of a stylus carriage as it is selectively incremented across a recording medium.

BRIEF DESCRIPTION OF THE DRAWINGS For a better understanding of the invention as well as objects and further features thereof, reference is made to the following description which is to be read in conjunction with the accompanying drawings and wherein:

FIG. 1 is an exploded view of the novel dual mode stylus drive system in accordance with the present invention;

FIG. 2 is the electrical control circuit for the drive system shown in FIG. 1; r

FIG. 3 is a bottom view of the novel stylus support member according to the present invention;

FIG. 3A is a partial cross-sectional view of FIG. 3;

FIG. 4 shows the drum shaft assembly described in FIG. 1; and

FIG. 5 shows the compose shaft assembly described in FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to FIGS. 1 and 2, there is shown an exploded view of the novel driving mechanism of the present invention with the supporting frame member omitted for clarity and a block diagram representation of the electrical control circuit for the driving mechanism, respectively. Motor 10 is the main mechanical power source in the driving system. A signal on lead rotates the compose and receive timing pulleys from which are driven all active system elements as hereinafter described. Coupled to the motor shaft by timing belt 12 are timing pulleys l4, l6 and 18. Timing pulley 14 is coupled to the input hub of a onerevolution spring clutch 20, the output hub of which is coupled to a cam or worm 22 having a cutout portion 24 thereon. The timing belt 12 also drives timing pulley 18 mounted to'the input hub of spring clutch 26. The

output hub of spring clutch 26 is coupled to gear 28, which is mounted to cable drum pulley 30 having grooves 31 and 33 thereupon. Adjacent to gear 28 and intermeshing therewith is gear 29, the function of which will be described hereinafter. A spring motor 32 is mounted to the other end of drum 30 and shaft encoder 34 is mounted to cam 22. The cable drum 30 wraps and feeds, along grooves 31 and 33, a stylus drive tape 36, the ends of which are anchored to drum 30. The tape 36 is maintained in tension and guided by pulleys 40, 42, 44 and 46. The other ends of the tape 36 are affixed to a carriage structure, or slider, 50 mounted within a slotted portion of carriage support member 52 for motion transverse to recording medium 54 in a reciprocating manner. It should be noted that the tape path for driving carriage slide 50 may be varied from that shown without departing from the spirit of the present invention.

A stylus 56, having a plurality of pins 58 thereon, is mounted to a stylus carriage arm 60 which is affixed to carriage slider 50. The carriage arm 60 serves as a mount for stylus S6 and interposer 62. The carriage support member 52 includes a plug, or cap, 67, at each end with a hole therein to enable the driving tape 36 to be connected to the carriage slider 50. Adjacent the carriage support member 52 is a backing electrode 63, the necessary recording potential being generated between stylus pins 58 and the backing electrode 63. The interposer 62 affects a plurality of reed switches 64, 66 and 68 by shunting associated magnetic field producing means 70, 72, and 74, respectively, as the carriage slider 50 moves within support member 52. An alternate technique of effecting switches 64, 66. and 68 would comprise substituting a magnet for interposer 62, eliminating the necessity of magnets 70, 72 and 74. The switches are located along the carriage slider travel for indicating the column position thereof and are positioned to correspond to 0, and 80 column positions on recording medium 54 when recording medium 54 is inserted into the apparatus as shown. It should be noted that additional switches may be positioned along the carriage slider travel for indicating additional column positions, as desired. An interposer 76, such as a pawl, engages a tooth space on gear 28 when the interposer is not actuated by solenoid 78, as will be described hereinafter. Recording medium 54 is indexed a row at a time by cam, or worm, 82 and gear 84, the cam and gear combination being coupled to the main motor by a one-revolution spring clutch :80. The

having a shaft speed of 1,800 revolutions per minute has been successfully utilized. The method of transmission and distribution of the shaft speed is through the timing belt 12. The system has a dual mode of operation as hereinafter will be described.

In the receive operational mode, wherein information is received from remote apparatus, the drive assembly comprises the cable drum 30 for wrapping and feeding the stylus drive tape 36, a wrap spring clutch 26 to drive the stylus in a forward direction, and a spring motor 32 to return the stylus to its initial position, corresponding to the 5 column position, after a line of alphanumeric. characters or symbols are printed electrostatically on recording medium 54. The ends of the stylus drive tape 36 are anchored to cable drum 30. The cable drum rotates through approximately three revolutions which will provide approximately 8 inches of print area per line of characters plus over shoot atclude a helical groove along the entire surface thereof to accommodate the cable as it winds and unwinds. The winding and unwinding of a cable on a helically grooved drum for various purposes is a well known technique. The pulleys 40, 42, 44 and 46 guide the tape from the cable drum 30 to the stylus carriage slider 50 and twist the tape into its proper position. The drum contains both ends of tape 36, the tape winding up on itself on groove 31 and unwinding off from groove 33. The wrap spring clutch 26 drives the stylus carriage slider 50 towards the right, or in the forward direction, as indicated by arrow 61, when it is engaged. The input hub of clutch 26 is driven by motor 10 through timing pulleys 16 and 18 at a constant speed. The spring porpressure and guide rollers, indicated generally at 90, i

and the roller drive mechanism, indicated generally at 92, are common printer and typewriter elements which may obviously be provided in a form different from that illustrated herein. Other means for supporting these members with relation to one another may be provided in accordance with well known conventional techniques without departing from the spirit and scope of the instant invention which relates more specifically to the means described for effecting drive of the across the recording medium 54 in accordance with the requirements for effecting proper printing.

The operational description of the driving system will now be described in more detail. Motor 10 is the main power source in the drive system and is chosen so that it is near several required system shaft speeds. A motor tion of the clutch has one end anchored to the input huband runs in clearance with the input and output hubs thereof. Clutch 26 is energized by the activation of solenoid 152 upon the closing of switch 64 when carriage slider 50 is at the 5 column position. The activated solenoid 152 causes an interposer to be pressed against the spring, forcing the spring to drag on the out put hub of the clutch add wrap the spring down, locking the input and output hubs of the clutch together, thereby driving the cable drum 30 through connecting gear 28. The deactivation of solenoid 152 by a signal indicating the transmitted information is completed allows the spring to unwind and release the cable drum 30 from the driving motor 10. A return mechanism 32, such as a clock spring, is wound as clutch 26 drives the stylus carriage slider 50 forward from the left, or initial position, corresponding to the 5 column position, towards the right. When the clutch 26 is disengaged, the spring motor 32 unwinds,

driving the stylus carriage slider 50 rapidly back towards the initial position, in the direction indicated by arrow 65. As carriage slider 50 moves reciprocally from left to right, interposer 62 shunts the magnetic fields generated by magnets 70, 72, and 74 effecting reed switches 64, 66 and 68. The effected switches generate electrical signals which areutilized to control various operations of the driving system as will be various operations in more detail hereinafter.

In the receive mode, digitally encoded data is fed from a control computer or other remote. apparatus to a terminal interface, such as standard data set 105. The term remote as used herein is intended to include all apparatus generating information to be rapidly printed other than that generated by keyboard 104. The data set is a commercially available item commonly emtype is, for example, available from the Bell System under the designation Model 201A Data Set.

The data set interface section is generally indicated by the numeral 107. This portion of the present system consists principally of input-output registers and an input router. In addition, conventional timing circuits, including a stable oscillator, electronic counters, and associated logic, are present within the interface section of the system. These elements are not explicitly indicated in view of the fact that the use of such clocking techniques to clock the data in and out of the registers is a technique commonplace and well understood by those skilled in the art of digital data manipulation. The computer furnished data maybe considered, for example, as generally made up of successive l0-bit words although in particular instances all of such bits need not be necessarily used in a functional sense. Thus in some typical instancesseven bits will represent a character,

one bit will be for parity purposes, and two bits will be surplusage. In an illustrative case the data is preceded by a routing word. This first word is decoded by the input router in interface 107 and indicates by its code whether the succeeding data should be routed to decoder 106 or to the solenoid inputs as shown. If routed to decoder 106, the decoded information is then transmitted to a character generator 108 which, when gated by clock 110, transmits pulses to stylus driving circuits 112 which drive appropriate stylus pins 58 to generate latent electrostatic alphanumeric characte and symbols on recording medium 54.

The keyboard 104 for generating characters in the compose mode may be any conventional keyboard for converting an actuated character key into a binary code, as is well known to those skilled in the art of generating digital data. The binary output from the keyboard and the received information from the remote apparatus are routed to decoder 106 which translates pin selection signals and provides a single output pulse for each character to be recorded. The output pulse generated by decoder 106 is fed to character generator 108 which conditions the circuits 1 12 driving the stylus to effect subsequent energization of associated stylus pins 58. Character generator 108 is a matrix of switching elements, such as flip-flops or magnetic cores, which operate to distribute the decoder output pulse to the particular switching elements which energize the stylus pins 58 to print a desired alphanumeric character or symbol on recording medium 54. The details of the decoder 106, character generator 108 and stylus driving circuits 112 have not been set forth as they are well known to those skilled in the art of digital data manipulation.

When the stylus carriage is at a column position corresponding to 3," the interposer 62 effects switch 64 and a signal, indicating that the stylus 56 is ready for operation, is coupled to one input of gate 116. A signal, indicating that the paper medium advance has been completed, generated by means not shown) is coupled to the other input of gate 116 and a signal is produced at the output thereof energizing solenoid 152, forcing the interposer on clutch 26 to engage the spring thereon, thereby wrapping down the spring and driving the cable drum 30. The stylus carriage slider 50, in the receive mode, is brought up to speed by the time the carriage reaches the 0 column position. When the stylus carriage 50 is at the 5 column position, the

signal generated by switch 64 is also coupled to the character generator clock 110, thereby conditioning the system for character generation when carriage slider 50 reaches the 0 column position.

When a receive complete signal is received on lead 120, clutch 26 is disengaged and the return mechanism 32 drives the stylus carriage slider 50 towards the initial, or -5 column, position. At the, "5column position, a ready signal is generated by connected to the input hubs of the paper feed onerevolution spring clutch 80 and the compose onerevolution spring clutch 20. When solenoid 122, controlling clutch 20, is pulsed by a signal on lead 124 when an operator actuates a key corresponding to an alphanumeric character or symbol on keyboard 104, cam 22 is driven through one revolution. The cam 22 drives gear 28, mounted-to the cable drum 30, moving the stylus carriageslider 50 one column position, or character, towards the right in the direction indicated by arrow 61. The paper feed clutch 80, when engaged, drives cam 82 and gear 84, advancing, or indexing, recording medium 54 one line position. The recording medium advance is initiated by the activation of solenoid 126 which engages the one-revolution spring clutch- 80 for any one of the following conditions. Upon activation of a backspace key on keyboard 104, solenoid 126 is pulsed for one pulse by a signal on lead 128. Upon activation of a next line key on keyboard 104, solenoid 126 is activated by a pulse appearing on lead 130. When a manual paper advance key is activated, solenoid 126 is energized by a signal appearing on lead 132, the solenoid being energized until the manual paper advance" key is inactivated. Finally, the solenoid 126 is energized by a signal on lead 120, indicating the completion of a transmitted message. The compose clutch 20, when engaged, moves the stylus carriage slider 50 one column to the right for each actuation thereof. One-revolution clutches 20 and 80 operate as follows. One end of a spring is anchored to the output hub of the clutch. When solenoid 122 is pulsed, an interposer disengages the spring by withdrawing from a returns and re-engages the spring end to limit the clutch to a single revolution. The inertia of cam 22 unwraps and expands the spring, disengaging it from the input hub. An anti-backup device is attached to earn 22 to prevent the backward rotation of cam 22 to inhibit the spring from draging on the input hub. The clutches as described and utilized in this invention are well known to those skilled in the mechanical arts.

Cam 22 has a gear tooth cross-section and is profiled to provide constant acceleration and deceleration of gear 28 The cam has a cutout portion 24 of approximately 30 which is chosen such that it is aligned with gear 28 when clutch is disengaged. This will allow gear 28 to turn freely to return the carriage slider 50 rapidly towards the left if the system is suddenly switched to the receive mode. An encoder 34 is mounted to earn 22 to break the column advance of carriage slider 50 into-7 increments of equal length ele- 'ments, 5 for character information. and 2 for intercharacter spacing in the compose mode. As cam 22 is rotated, the encoder generated pulses areconnected to thecharacter generator clock 110 wherein the pulse rate of the clock is reduced from a high rate to the required seven pulses percharacter. This conditions the character generator 108 to emit character information at the proper time, compensating for the varying velocity of the stylus slider 50 as it moves one column position and preventing distortion of the generated character. Altemately, the output of encoder 34 may be coupled to character generator 108 via lead 11 l, the output of the character generator being generated at a time interval directly determined by the output of encoder 34. Encoder 34 is not necessary in the receive mode since the stylus slider 50 is brought up to constant'speed at the 0 column position when printing is initiated, as described hereinabove and the character printed will generally not be distorted. Encoder 34 can be constructed in any known manner and can include, for example, a wheel having seven inserts of "magnetic susceptible material on its peripheral surface and a magnetic induction sensor adjacent thereto for generating seven pulses for every revolution of the wheel. Altemately, the encoder 34 can take the form of a wheel member composed of seven vanes, each vane actuating an adjacent sensor.

The anti-backup mechanism comprises a solenoid I controlled interposer 76, such as a pawl, for engaging gear 28 and preventing clock spring 32 from returning the carriage slider towards the initial position when clutch 20 disengages after a single revolution. Drive cam 22 advances gear 28 slightly more than one tooth pitch, allowing interposer 76 to drop in behind the next tooth. Since the gear and cutout portion of cam 22 are aligned when cam 22 comes to rest, return spring 32 drives gear 28 back against interposer 76.

The operation of the drive system in either mode commences with the activation of a key on keyboard 104 connecting a source of power to the main drive motor 10 via lead 100. The carriage slider 50 is initially at rest in the compose mode at the 0 column position. The single revolution, solenoid actuated clutch 20, located on the compose shaft, is normally disengaged as solenoid 122 is not actuated. Activation of any keyboard character key provides a pulse to solenoid 122, permitting the engagement of clutch 20. In the receive mode, the carriage slider is initially at rest at the 5 column position and upon receipt of printing information at data set 105, clutch 26 is engaged as described previously. in the compose mode, clutch 20 may also be activated by a stylus advance-repeat series of pulses, appearing on lead 134 when a keyboard key is actuated, which is utilized after an error on the printed line is corrected to return the stylus to the original location without changing the information stored in the compose memory unit, utilize for storing the information to be printed, in an incremental fashion.

The anti-backup solenoid 78 is activated by signals from any one of three sources as follows. Activating the keyboard backspace key pulses the interposer solenoid 78 via lead 128 which allows the stylus carriage return spring 32 to move the stylus right to left one character space. The backspace solenoid 78 may also be activated via lead 140 during the receive mode when a message is being received from the remote apparatus, permitting free reciprocation of the stylus carriage. The

receive signal also starts the character clock via lead 142. The third condition for activating solenoid 78 is in the compose mode at the completion of the last character of a given line when it is desired to return the stylus carriage to the O colunm position. The solenoid 78, in thissituation, is energized by a next line signal on lead 130. This signal also locks out the keyboard by engaging the keyboard lockout switch shown in FIG. 2, preventing the entry of any information via the keyboard and inhibits the character clock 110 via leads M6 and 148, respectively. Solenoid 78 remains in this state until deenergized by a signal generated by switch 66 corresponding to the 0 column position.

A stylus carriage stop solenoid 150 is utilized to stop the carriage slider 50 at the 0 column position when the system is in the compose mode. The solenoid is energized continuously via lead 141 when the system enters the receive mode. Solenoid 150 is released, or

deenergized, when it is signalled via a signal on lead that the receive message is complete. The solenoid, when deenergized, stops the rotation of gear 28 when carriage slider 50 is at column position 0. The operation of the stop member will be described in more detail with reference to FIG. 5, discussed hereinafter.

Solenoid 152 controls the high speed, or receive mode, clutch 26 and is energized and held by the closing of reed switch 64, corresponding to the -5 column position, provided that the paper advance has been completed. The energizing signal is provided at the output of gate 116 which provides an output signal when the -5 column signal and the feed complete signal (generated by means not shown) appears at the input of gate 116. The high speed solenoid 152 is released by a signal on lead 154 generated when switch 68, corresponding to the 80 column position, is reached or when signalled via signal on lead 120 that the received message has been completed.

The stylus retract solenoid 156 is energized by a signal on lead 158 and held by the arrival of the carriage slider 50 at column position 80 or by a new line signal via lead 131. When solenoid 156 is energized, carriage support 52 is rotated partially to lift stylus 56 off the recording medium 54. The solenoid 156 may be linear or rotary and actuates arm 157, connected to carriage support 52, which rotates the support. Solenoid 156 is released by a signal generated by switch 66 on lead 155, corresponding to the column position, if the carriage slider 50 is moving from right to left.

The column position switch 64, in addition to its functions described previously, when triggered by the stylus carriage slider 50, generates a pulse on lead 162 which must be recognized before character clock 1 can run.

The 0 column switch 66, in addition to its previously described functions, conditions the character clock 110 via lead 164 and also releases the keyboard lockout switch via a signal on lead 166.

The 80 column switch 68, when activated by the carriage slider 50, generates a signal on lead 168 to stop the character j clock 110 and locks out the keyboardto inhibit further entry of characters or codes viaa signal-on lead 170, in addition to its previously described functions.

Apparatus for. developing the electrostatic'latent characters deposited upon the recordingmedium 54' has not been shown since it does not form part of the present invention. However, any suitable development system may be used, such as the system disclosed in U. S. Pat. No. 3,289,209. The composition of the recording medium has not been set forth in detail since it does form part of the present invention. However, it should have the characteristic or retaining electrostatic charge deposited on the working surface thereof.

It also should be realized that an electrosensitive medium may be utilized as the recording medium whereby current flow between the stylus pins 58 and the backing electrode 63 causes the surface of the electrosensitive medium to darken or change color where the styli pins engage the medium surface, to provide legible distinct marks thereat. This eliminates the necessity for development apparatus of the type described hereinabove.

Referring now to FIG. 3, there is shown a bottom view of the stylus support member 52. Visible in this view is the elongated slot portion 200 extending along a substantial portion of the surface. Drive tape 36 is affixed to the carriage slider 50 at 202 and 204. Retaining means, or plugs, 67 are inserted at each end of member 52 to form an air compression chamber. Afiixed to plugs 67 are resilient bumpers 209, made, for example, from compressible rubber, to partially absorb the energy of slider'50 as it reaches either end of tube 52. As the carriage slider 50 is driven from left to right or right to left at a high speed, a flexible cup 208, shown in more detail in FIG. 3A, and affixed to the carriage slider 50 at each end thereof, passes relief ports 210. The air pressure ahead of cup 208 increases, causing cup 208 to expand and the air .to compress, decreasing the clearance between slider 50 and the inside of tube 52. Cup 208 may be eliminated if very close clearances are maintained between slider 50 and tube 52. The

decrease in clearance improves pneumatic dampening and the friction between the cup 208 and the inside wall 210 of tube 52 also acts to slow down the carriage slider 50. An additional relief port 207 is provided at the left end of tube for slowing the carriage slider 50 when, in the compose mode, it is desired to slow the slider as it reaches the 0 column position. The left relief port 210 is closed in the compose mode by actuation of a solenoid. The solenoid, by appropriate linkages, forces a member, such a rubber plug 213, over left relief port 210. The air ahead of relief port 207 now is compressed, slowing down slider 50. In the receive mode, all the relief ports remain open, the carriage slider 50 slowing down as described hereinabove. The

solenoid for actuating member 213 is not shown in the figure but is similar to the other solenoids described previously, and may be actuated by the receive complete signal described in reference to FIG. 2. The cup 208 is preferably made of a flexible material, such as urethane, although other materials may be utilized. The volume of the support member 52 in which the air is compressed in the receive mode is indicated by I and may be considered the air compression chamber. A similar volume, not shown, is present on the left side of member 52. In the compose mode, the volume on the left side of support member 52 is increased because of the-addedrelief port 207, as described above. The stylus carriage arm 60 extends through slot 200 and is affixed to carriage slider 50. The carriage slider 50 is preferably madeof plastic although other materials may be used.- Slider 50, by moving inside support member 52, reduces dirt contaminationwhen compared to an external slider. The carriage member 52, although illustrated as a cylindrical tube, may be formed in various geometric shapes and is preferably made of aluminum, although other materials may be used. Although not shown' in the FIG. 3, the ends of support member 52 include bearings to enable it to pivot, keeping friction minimal, when it is required to retract the stylus, as described hereinabove. For the sake of clarity, bearing members utilized in theshaft assemblies described above have also been omitted from the drawing.

Referring now to FIG. 4, the drum, or receive, shaft assembly is shown in detail. The Figure shows the eutout portion 24 of worm 22 aligned with worm gear 28. The worm 22 attains this position after completing one revolution and when the system is operating in the receive mode. Clutch 26 is shown in partial cross-section to illustrate the operation of a wrap down spring clutch. The clutch 26 comprises input and output hubs 220 and 221, respectively. A spring 224 has one end 226 anchored to input hub 220 and the other end inserted in an aperture in plastic coating, or sleeve, 242. When solenoid 152 is energized, a spring biased interposer 228, or brake strap, is pressed. against spring 224. The pressure of interposer 228 on spring 224 forces the spring to be wrapped down on the input and output hubs 220 and 221, thereby coupling the hubs together and rotating the drum shaft assembly about shaft 230. The whole assembly is mounted on a suitable frame or bracket not shown in FIG. 1. The plastic coating 242 encapsulates the spring clutch to prevent undue wear thereon.

Referring now to FIG. 5, there is shown the compose shaft assembly illustrating more clearly the elements on the compose shaft assembly. The interposer, or pawl 76, is biased by spring to rest behind a gear tooth space. When solenoid 78 is energized, interposer 76 is withdrawn from the tooth space and the gear 28 is allowed to rotate freely as long as the interposer is withdrawn. The interposers associated with solenoids 122 and 126 are controlled thereby and act to engage and disengage the dogs, or projections, on sleeves 246 and 248, respectively, effecting the respective onerevolution clutch springs as described hereinabove.

A stop member, such as indicated generally by 247, functions to stop the carriage slider 50 at the column position when the system is in the compose mode. A spiral groove 254, having arcuate portions 258 and 260 included thereon, is cut into the face of gear 29. A pin 250 is biased by spring 256 to ride on the inside surface 251 of the spiral groove while the system is in the compose mode. The pin 250 is shown in a position corresponding to the slider position as shown in FIG. 1. If it is assumed that the carriage slider is retum ing to the initial, or left position, the pin 250 is traveling in a counterclockwise direction inside the spiral groove 254. When the pin 250 reaches surface 258, corresponding to the slider at column position 0, the pin is prevented from moving any further, thereby stopping gear 29 and slider '50. In the receive mode, solenoid 150 is continuously energized and arm 252 moves the pin slightly away from surface 251. In this situation, the pin 250 is enabled to travel past surface 258 and come to rest at surface 260. If surface 260 is positioned to correspond to the -'5 slider column position, stop member 247 acts to stop slider 50 at the column position in the receiver mode.

When the carriage slider 50 is traveling in the forward direction, or from left to right, the gear 28 rotates in a counter clockwise direction and pin 250 moves freely in the spiral groove 254. In this case, member 247 may act as a positive stop for carriage slider 50 at column position 80 if the length of spiral groove is adjusted accordingly.

The invention described hereinabove provides a novel dual mode printing apparatus compatible with high speed data generation and transmission systems. In the receive mode, speeds of greater than five lines per second have been attained. Assuming an 80 character line, this means that more than 400 characters per second may be printed.

While the invention has been described with reference to its preferred embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the true spirit and scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teaching of the invention without departing from its essential teachings.

What is claimed is: i

1. Apparatus for printing characters in spaces on a recording medium, said apparatus being selectively operable in either a low or high speed mode of operation, comprising:

a carriage slider having a stylus mounted thereon,

support means located adjacent said recording medium for supporting said carriage slider,

a first drive mechanism for selectively driving said carriage slider at a substantially constant rate across the recording medium between a first and second position on said support means, said first drive mechanism being operable in said high speed mode of operation,

a second drive mechanism for selectively driving said carriage slider incrementally across the recording medium between said first and second positions on said support means, said second drive mechanism being operable in said low speed mode of operation,

motor means for selectively driving said first or second drive mechanisms when coupled thereto,

first means responsive to a first control signal for selectively coupling said motor means to said first drive mechanism for a first time period in said high speed mode of operation, said first time period being greater than that required to move said stylus continuously across one of said spaces, said stylus being actuated by a first input signal to print at least one character during said first time period, and

second means-responsive to a second control signal for selectively coupling said motor means to said second drive mechanism for a second time period in said low speed mode of operation, said second time period being that required to move said stylus an increment equal to a single one of said spaces, said stylus being actuated by a second input signal to print a single character during said second time period.

2. The apparatus as defined in claim 1 wherein said second input signal is generated by actuation of a single character key on a keyboard.

3. The apparatus as defined in claim 2 wherein said first input signal is generated by means responsive to data transmitted from apparatus remote from said printing apparatus.

4. The apparatus as defined in claim 1 wherein said support means comprises a tubular member having a slot along a portion of the surface thereof, said carriage slider being driven within said slot between said first and second positions.

5. The apparatus as defined in claim 4 wherein said tubular member further includes means for retaining a compressible fluid medium at each end thereof, said medium being compressed within the non-slotted portion of said tubular member as said carriage slider moves towards either said first or second position, the compressed medium slowing the speed of the carriage slider as it nears said first or second position.

6. The apparatus as defined in claim I and including means for retracting said stylus from the recording medium during the return of said carriage slider to said first position.

7. The apparatus as defined in claim 1 wherein each character space comprises a plurality of equal length elements and further including means for generating an electrical pulse each time said stylus moves a distance equal to the length of a single element when said motor means is coupled to said second drive mechanism, each pulse actuating the stylus so that a portion of said single character is printed at a corresponding element.

8. The apparatus as defined in claim 1 wherein said first and second coupling means comprise first and second clutch means, respectively.

9. Apparatus for printing characters in spaces on a recording medium comprising:

a carriage slider having a stylus mounted thereon,

support means located adjacent said recording medium for supporting said carriage slider,

a drive mechanism for driving said carriage slider across said record medium between a first and second position on said support means,

means responsive to a control signal for selectively riage slider being driven within said slot between a first and second position, said tubular member including means for retaining a compressible fluid medium at each end thereof, whereby said medi- P Said drive mechanism Period of time 5 um is compressed within the non-slotted portion of requlred move f stylus an Increment equal to said tubular member as said carriage slider moves a FP of sald spacesl, each Character space towards either said first or second position, the cqmpnsmg a Plurahty of equal f elfimemsi compressed medium slowing the speed of the cari Styhjls bemg actuated by an mput Slgnal to riage slider as it approaches said first or second print a single character during said time period, 10 position and a drive mechanism for driving said carriage slider means 9nnected Sald responslfe f across said recording medium between said first generating an electrical pulse each tunesatd stylus and Second positions on Said Support means moves a dlstance equal leflgth ofa Smgle motor means for driving said drive mechanism when ment, each pulse actuating said stylus so that a coupled thereto and gg g g zig i character pnmed at a means responsive to a control signal for coupling said p0 g motor means to said drive mechanism, said stylus The apparatus as-defined m dm 9 wherem sald bein actuated to rint characters on said recordinput signal is generated by'the activation'of a single mg edium as thepstylus is driven theteacross y character key on a keyboard. I

11. The apparatus as defined in claim 9 wherein said support means comprises a tubular member having a slot along a portion of the surface thereof, said carriage slider being connected for movement within the slot 2 between said first and second positions. 1

12. Apparatus for printing characters in spaces on a recording medium comprising:

' a carriage slider having a stylus mounted thereon,

said drive mechanism.

14. Apparatusfor printing characters in spaces on a recording medium, said apparatus being selectively operable in either a low or high speed mode of opera- 5 tion, comprising:

a carriage slider having a stylus mounted thereon,

support means located adjacent said recording medium for supporting said carriage slider,

support means located adjacent said recording medium for supporting said carriage slider, said support recording medium means comprising a tubular member having a slot motor means energizing Said driving means when along a portion of the surface thereof, said carwupled thereto, riage slider being connected for movement within first clutch means responsive to a fu'st control signal the slot between a first and second position on said for selectively coupling said motor means to said support means, said tubular member further indriving means for a first time period in said high cluding means for retaining a compressible fluid speed mode of operation, said first time period medium at each end thereof, whereby said medibeing greater than that required to move said styum is compressed the non-slotted portion Of lug continuously across one of spaces ty- Said tubular member as Said r g slide! moves 40 lus being actuated by a first input signal to print at towards either said first 01 second position, the I least one character during aid time period, and compressed mafium slowing the speed of the second clutch means responsive to a second control Slider as it pp said first Second signal for selectively coupling said motor means to pqsmon, said driving means fora second time period in said a dnve mefihamsm for djnvmg 531d m shder low speed mode of operation, said second time across said record medium between said first and period being that required to move Said Stylus an Second posltions on sald suppoit means l increment equal to a single one of said spaces, said i raspqnslv? to a contiol Sign for.selecm.lely stylus being actuated by a second input signal to driving said drive mechanism for a period of time so prima single character during said Second time required to move said stylus an increment equal to a single one of said spaces, each character space comprising a plurality of equal length elements, said stylus being actuated by an input signal to print a single character during said time period, and

means connected to said responsive means for generating an electrical pulse each time said stylus moves a distance equal to the length of a single element, each pulse actuating said stylus so that a portion of said single character is printed at a corresponding element. v

13. Apparatus for printing characters electrically on a recording medium comprising:

a carriage slider having a stylus mounted thereon,

support means located adjacent said recording medium and comprising a tubular member having a slot along a portion of the surface thereof, said carmeans for driving said carriage slider across said period.

15. The apparatus as defined in claim 14 further including a rotatable driven member connected to said first clutch means and a rotatable driving member connected to said second clutch means, said first clutch means being coupled to said driving means by said rotatable driven member and said second clutch means being coupled to said driving means by the interface of said rotatable driving member with said rotatable driven member.

16. The apparatus as defined in claim 15 further including an actuable interposer for engaging said rotatable driven member when said second clutch means selectively couples said motor means to said driving means and after said stylus moves said one character space, thereby preventing said stylus from returning towards said first position.

ing a compressible fluid medium at each end thereof, said medium being compressed within the non-slotted portion of said tubular member as said carriage slider moves towards either said first or second position, the compressed medium slowing the speed of the carriage slider as it nears said first or second position. 

1. Apparatus for printing characters in spaces on a recording medium, said apparatus being selectively operable in either a low or high speed mode of operation, comprising: a carriage slider having a stylus mounted thereon, support means located adjacent said recording medium for supporting said carriage slider, a first drive mechanism for selectively driving said carriage slider at a substantially constant rate across the recording medium between a first and second position on said support means, said first drive mechanism being operable in said high speed mode of operation, a second drive mechanism for selectively driving said carriage slider incrementally across the recording medium between said first and second positions on said support means, said second drive mechanism being operable in said low speed mode of operation, motor means for selectively driving said first or second drive mechanisms when coupled thereto, first means responsive to a first control signal for selectively coupling said motor means to said first drive mechanism for a first time period in said high speed mode of operation, said first time period being greater than that required to move said stylus continuously across one of said spaces, said stylus being actuated by a first input signal to print at least one character during said first time period, and second means responsive to a second control signal for selectively coupling said motor means to said second drive mechanism for a second time period in said low speed mode of operation, said second time period being that required to move said stylus an increment equal to a single one of said spaces, said stylus being actuated by a second input signal to print a single character during said second time period.
 2. The apparatus as defined in claim 1 wherein said second input signal is generated by actuation of a single character key on a keyboard.
 3. The apparatus as defined in claim 2 wherein said first input signal is generated by means responsive to data transmitted from apparatus remote from said printing apparatus.
 4. The apparatus as defined in claim 1 wherein said support means comprises a tubular member having a slot along a portion of the surface thereof, said carriage slider being driven within said slot between said first and second positions.
 5. The apparatus as defined in claim 4 wherein said tubular member further includes means for retaining a compressible fluid medium at each end thereof, said medium being compressed within the non-slotted portion of said tubular member as said carriage slider moves towards either said first or second position, the compressed medium slowing the speed of the carriage slider as it nears said first or second position.
 6. The apparatus as defined in claim 1 and including means for retracting said stylus from the recording medium during the return of said carriage slider to said first position.
 7. The apparatus as defined in claim 1 wherein each character space comprises a plurality of equal length elements and further including means for generating an electrical pulse each time said stylus moves a distance equal to the length of a single element when said motor means is coupled to said second drive mechanism, each pulse actuating the stylus so that a portion of said single character is printed at a corresponding element.
 8. The apparatus as defined in claim 1 wherein said first and second coupling means comprise first and second clutch means, respectively.
 9. Apparatus for printing characters in spaces on a recording medium comprising: a carriage slider having a stylus mounted thereon, support means located adjacent said recording medium for supporting said carriage slider, a drive mechanism for driving said carriage slider across said record medium between a first and second position on said support means, means responsive to a control signal for selectively driving said drive mechanism for a period of time required to move said stylus an increment equal to a single one of said spaces, each character space comprising a plurality of equal length elements, said stylus being actuated by an input signal to print a single character during said time period, and means connected to said responsive means for generating an electrical pulse each time said stylus moves a distance equal to the length of a single element, each pulse actuating said stylus so that a portion of said single character is printed at a corresponding element.
 10. The apparatus as defined in claim 9 wherein said input signal is generated by the activation of a single character key on a keyboard.
 11. The apparatus as defined in claim 9 wherein said support means comprises a tubular member having a slot along a portion of the surface thereof, said carriage slider being connected for movement within the slot between said first and second positions.
 12. Apparatus for printing characters in spaces on a recording medium comprising: a carriage slider having a stylus mounted thereon, support means located adjacent said recording medium for supporting said carriage slider, said support means comprising a tubular member having a slot along a portion of the surface thereof, said carriage slider being connected for movement within the slot between a first and second position on said support means, said tubular member further including means for retaining a compressible fluid medium at each end thereof, whereby said medium is compressed within the non-slotted portion of said tubular member as said carriage slider moves towards either said first or second position, the compressed medium slowing the speed of the carriage slider as it approaches said first or second position, a drive mechanism for driving said carriage slider across said record medium between said first and second positions on said support means, means responsive to a control signal for selectivEly driving said drive mechanism for a period of time required to move said stylus an increment equal to a single one of said spaces, each character space comprising a plurality of equal length elements, said stylus being actuated by an input signal to print a single character during said time period, and means connected to said responsive means for generating an electrical pulse each time said stylus moves a distance equal to the length of a single element, each pulse actuating said stylus so that a portion of said single character is printed at a corresponding element.
 13. Apparatus for printing characters electrically on a recording medium comprising: a carriage slider having a stylus mounted thereon, support means located adjacent said recording medium and comprising a tubular member having a slot along a portion of the surface thereof, said carriage slider being driven within said slot between a first and second position, said tubular member including means for retaining a compressible fluid medium at each end thereof, whereby said medium is compressed within the non-slotted portion of said tubular member as said carriage slider moves towards either said first or second position, the compressed medium slowing the speed of the carriage slider as it approaches said first or second position, a drive mechanism for driving said carriage slider across said recording medium between said first and second positions on said support means, motor means for driving said drive mechanism when coupled thereto, and means responsive to a control signal for coupling said motor means to said drive mechanism, said stylus being actuated to print characters on said recording medium as the stylus is driven thereacross by said drive mechanism.
 14. Apparatus for printing characters in spaces on a recording medium, said apparatus being selectively operable in either a low or high speed mode of operation, comprising: a carriage slider having a stylus mounted thereon, support means located adjacent said recording medium for supporting said carriage slider, means for driving said carriage slider across said recording medium, motor means for energizing said driving means when coupled thereto, first clutch means responsive to a first control signal for selectively coupling said motor means to said driving means for a first time period in said high speed mode of operation, said first time period being greater than that required to move said stylus continuously across one of said spaces, said stylus being actuated by a first input signal to print at least one character during said time period, and second clutch means responsive to a second control signal for selectively coupling said motor means to said driving means for a second time period in said low speed mode of operation, said second time period being that required to move said stylus an increment equal to a single one of said spaces, said stylus being actuated by a second input signal to print a single character during said second time period.
 15. The apparatus as defined in claim 14 further including a rotatable driven member connected to said first clutch means and a rotatable driving member connected to said second clutch means, said first clutch means being coupled to said driving means by said rotatable driven member and said second clutch means being coupled to said driving means by the interface of said rotatable driving member with said rotatable driven member.
 16. The apparatus as defined in claim 15 further including an actuable interposer for engaging said rotatable driven member when said second clutch means selectively couples said motor means to said driving means and after said stylus moves said one character space, thereby preventing said stylus from returning towards said first position.
 17. The apparatus as defined in claim 14 wherein said support means comprises a tubular member having a slot along a portion of the surface thereof, said carriage slider bEing driven within said slot between a first and second position.
 18. The apparatus as defined in claim 17 wherein said tubular member further includes means for retaining a compressible fluid medium at each end thereof, said medium being compressed within the non-slotted portion of said tubular member as said carriage slider moves towards either said first or second position, the compressed medium slowing the speed of the carriage slider as it nears said first or second position. 